This is a snipit from an RP that my friend and I have been working on, however everything here is stuff that I wrote. The girl in this is intentionally left ambiguous, and in the original take of this, she was in fact NOT a love interest, so it doesn't even have to be shipping.
During the scuffle, Clint tried to fire an arrow at an AIM agent that was getting too close for his comfort. However, right as it was fired, another agent fell into him. Clint watched in horror as the arrow DIDN'T hit its intended target, and instead sailed into a piece of machinery on the far wall. There was a spark, then the machine caught on fire. This was apparently enough to set off the explosives in the room, starting with those on the side that she was on. Clint shouted her name as the ceiling caved in on her. He tried to run over, but Tony dragged him away, flying him back outside with the other Avengers and a few lucky AIM got out just in time - the whole building collapsed, and Thor even had to take off his cape because some of it became caught in the rubble.
As soon as everything settled, Tony let Clint run back out into the mess to shift through, on the faint hope she was alive. He managed to find her arm in the rubble - barely recognizable due to the blood and crushed bones. There was no way she could've survived. A proper burial would've even proved difficult, due to how mangled her body must be. Clint began to cry, not letting anyone near him.
Janet and Hank had eventually managed to drag Clint away from the rubble. However, when they got back to the Avengers mansion, he shut himself in his room and refused to talk to anyone. There was a cloud of depression over the rest of the Avengers as well. Cap seemed to be the next most depressed about it, having flashbacks to losing Bucky. However, this time it seemed even more real due to actually seeing part of the body. Janet would not let go of the charm bracelet that Clint had given their now-lost friend, each charm representing a different Avenger, as if her life depended on it. She didn't even put it on - she just clutched it in her hand and occasionally stared at it. Tony was the one to spread the news to Bruce and Fury. Bruce seemed overwhelmed by the news and had a hard time keeping the Hulk under control, but he managed to. Thor grieved in his own quiet, stoic way, as did Hank.
Janet went once again to try to get Clint to get out of his room. "There's something you should probably have."
Clint opened the door with enough force to startle Janet. "What? What do you have?" he asked, obviously irritated. Janet wordlessly held out the charm bracelet, which Clint took. It caused him to have to fight to hold back more tears, and he sat down on his bed, keeping the door open. Janet cautiously walked in, her own face still stained from tears. "It's my fault," Clint realized. "I missed my shot, and it caused the whole damn building to collapse."
"That guy fell into you," Janet pointed out. "It wasn't your fault you missed the shot."
"If I had fired just one moment earlier, or waited just one moment, she would be alive," Clint stated. "I don't miss. I CAN'T miss. Because then, stuff like this happens." He was clutching the bracelet so hard that the charms dug into his skin, the bow and arrow charm, due to it being the sharpest of the charms, managed to draw blood without Clint even noticing.
At this moment, this remans a oneshot. However, I have been considering expanding this out to a full fanfic. The only issue is that I'd be writing it as a romantic fic, with the girl being a blatant self-insert OC, which is usually frowned upon in the world of fanfic writing.